This invention relates generally to improved digital communication means and methods, and more particularly to improved means and methods useful for providing reliable, high speed transmission of digital data between units in a digital data processing system operating in a high noise environment.
Modern data processing systems have a number of different units between which binary digital data must be reliably communicated at high speed. Although parallel digital data communication has been employed in the prior art for providing digital data communication between data processing units, the current trend is toward the use of more serial-type transmission systems because of the cost and inconvenience of parallel communication systems, particularly where communication is required to be provided over distances greater than 100 feet. However, in order to make such serial-type digital data communication compatible with the speed capabilities of modern data processing systems, it is important that such a serial-type system be capable of providing relatively high digital data transmission rates. An example of an advantageous system of this type is disclosed in the commonly assigned copending applications Ser. No. 737,730, Ser. No. 737,731, Ser. No. 737,732 and Ser. No. 737,783, all filed on Nov. 1, 1976.
Although a variety of approaches and circuitry are known in the art for implementing a serial-type digital data transmission system, including the advantageous system referred to above, the prior art has nevertheless continued to experience considerable difficulties in providing a reliable, economically feasible high speed serial data transmission system, particularly where the system is required to operate in a high noise environment.